So the last month and a half I been getting 10.5 to 13 mpg. These is no cell on. I run 93Oct. IM only getting about 180 200to a tank. There is no had leak. Maybe thermostat is . It's killing me I do I've 350 Miles a week to work. only thing done to truck are fox shocks and 3 in lift. And drop in filter. Keep it under 2000RPMs and under 60. I know it's winter but come on. I let it run 5 min to warm up. Any one have a clue what it could be. I was getting 15 18 mpg before truck started to hate the world. Just hope it's bad has.

Octane isn't an energy rating. Higher octane fuel just handles compression better, that is why it is required in boosted and high compression engines. There is a chance that your higher octane is ethanol free though in which case that explains the better fuel economy.

Every mod I do, I lose fuel economy... The lift hurts your aerodynamics, tires hurt your aerodynamics and your rotating weight, etc... It adds up... I was getting about 16-17 mpg in the summer and am getting about 11-13mpg now in the winter... All on the cheap octane. Our vehicles must really dislike the winter blend is all I can figure...